1. Field of the Invention
The present invention relates to a toner cartridge assembly and a printing apparatus.
2. Description of the Related Art
A conventional printing apparatus using an electrophotographic method such as a laser printer, a photocopying machine, or a facsimile machine develops a desired image by developing an electrostatic latent image with a developing agent, after forming the electrostatic latent image by projecting a laser beam on a photosensitive medium such as a photosensitive drum. The image developed on the photosensitive medium is transferred to a printing paper passing through to a transfer nip between the photosensitive medium and a transfer roller, and is settled on the printing paper at a settlement unit.
The printing apparatus has a developing cartridge to form the image. Referring to FIG. 1, the conventional developing cartridge has a developing unit and a toner supplying unit including a cartridge body 10. The cartridge body 10 has a charging roller 12, a developing roller 13, and a cleaning blade 14, all surrounding a photosensitive drum 11.
Moreover, inside of the cartridge body 10, there is a used toner chamber 10a at one side of the photosensitive drum 11 and a new toner chamber 10b at another side of the photosensitive drum 11.
According to the above structure, the photosensitive drum 11 is charged by the transfer roller 12, and an electrostatic latent image is formed on one side thereof by a light charging roller 12, and an electrostatic latent image is formed on one side thereof by a light projected from a laser projection unit (not shown). In addition, a visible image is formed at the electrostatic latent image area as toner supplied from the new toner chamber 10b is transferred by the developing roller 13. The formed visible image is copied to the paper P passing through between the photosensitive drum 11 and a developing roller 20.
In the meantime, in the developing cartridge having the above structure, the elements inside of the cartridge body 10 are manufactured together, and when the toner is used up, the entire cartridge is exchanged. Therefore, the elements cannot be individually exchanged. Accordingly, a contact status (hereinbelow, referred to as a developing nip) between the photosensitive drum 11 and the developing roller 13 is compulsorily regulated.
However, according to the above structure, as the photosensitive drum 11 and the developing roller 13 are installed to be fixed at the cartridge body 10, the developing nip between the photosensitive drum 11 and the developing roller 13 is irregular, thus there are problems caused by the developing nip.
The irregular developing nip is caused by run out of the elements of the photosensitive drum 11 and the developing roller 13. In other words, the run out of the photosensitive drum 11 cannot be reduced within 0.05 mm, and the run out of the developing roller 13 reaches up to 0.1 mm. When two elements are united, the developing nip in a lengthwise direction of the photosensitive drum 11 is 0-0.15 mm.
When the developing nip in the developing cartridge of a contact developing method is zero, the toner on the developing roller 13 can be theoretically developed on the photosensitive drum 11. Yet, in practice, the toner can be developed when the overlapping volume of a distance between axes of the developing roller 13 and the photosensitive drum 11 is at least 0.05 mm.
Therefore, the developing nip is within the range of 0.05 mm to 0.2 mm as the overlapping volume of the distance between the axes, the developing roller 13 and the photosensitive drum 11 have a contact area having 0.05 mm of the overlapping volume and another contact area having 0.2 mm of the overlapping volume. Furthermore, there is a large difference in the mechanical power that the toner receives at a contact area having different overlapping volumes from each other.
If the developing nip is irregular in the lengthwise direction of the photosensitive drum 11, the toner cannot stably settle on the photosensitive drum 11 when the toner is transferred from the developing roller 13 to the photosensitive drum 11, and the toner is removed or recollected to the developing roller 13. Therefore, there is a problem in the image, specifically, the density of the image is not uniform, or the image is distorted.
Accordingly, it is an object of the present invention to overcome the above-mentioned problems of the prior art.
It is another object of the present invention to provide a toner cartridge assembly and a printing apparatus having an improved structure to maintain the developing nip as the toner cartridge assembly is settled by being separated from a photosensitive drum cartridge.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a toner cartridge assembly installed to correspond to a photosensitive drum cartridge disposed at a printing apparatus body, the toner cartridge assembly to develop toner on the photosensitive drum and collect used toner on the photosensitive drum, the toner cartridge assembly including a toner cartridge to correspond to the photosensitive drum cartridge at the body, having a developing roller to develop the toner on the photosensitive drum, a developing nip being formed between the developing roller and the photosensitive drum; and a used toner chamber movably connected to a side of the toner cartridge, the used toner chamber to store the used toner collected from the photosensitive drum cartridge, wherein the used toner chamber is fixed to the printing apparatus body, and the toner cartridge adjusts the developing nip by being connected with the used toner chamber such that the toner cartridge reciprocates and rotates in a direction of the photosensitive drum.
According to an aspect of the present invention, the toner cartridge reciprocates for a predetermined distance and rotates in relation to the used toner chamber.
According to another aspect of the present invention, the toner cartridge assembly further includes a first screw; a second screw; a first boss connected with the first screw to guide the reciprocation and the rotation of the toner cartridge; a second boss connected with the second screw to guide the reciprocation of the toner cartridge and to regulate a rotation angle of the toner cartridge, the first and second bosses being disposed at the side of the toner cartridge; a longitudinal hole formed in the used toner chamber to guide the reciprocation of the toner cartridge by being connected with the first screw; and a reaming hole formed in the used toner chamber to limit the rotation angle of the toner cartridge by limiting a range of movement of the second screw.
The toner cartridge assembly may further include a flange portion having a greater diameter than the longitudinal hole and the reaming hole, formed at each head portion of the first and second screws.
The toner cartridge assembly may further include a position deciding unit relatively coupled with a predetermined position of the body in order to fix a settlement position when being installed at the body.
According to yet another aspect of the present invention, the position deciding unit includes a pair of position deciding holes disposed at an upper part of the used toner chamber in order to be relatively connected with position deciding pins disposed at a predetermined area of the body.
The toner cartridge assembly may further include portions, disposed at an outer side of the toner cartridge, stepped in a direction in which the toner cartridge is installed at the body. The stepped portions guide the toner cartridge to the photosensitive drum cartridge when being installed at the body.
The foregoing and other objects of the present invention are also achieved by providing a printing apparatus including a body having first and second cartridge settlement units connected with each other; a photosensitive drum cartridge removably installed at the first cartridge settlement unit and having a photosensitive drum to be exposed to an outside thereof; a toner cartridge assembly removably installed at the second cartridge settlement unit, having a developing roller contacted with the photosensitive drum in order to form a predetermined developing nip and adjusted to a position thereof while being installed; and a press unit to maintain the developing nip by pushing the toner cartridge towards the photosensitive drum when the toner cartridge assembly is installed.
According to an aspect of the present invention, the printing apparatus further includes a used toner chamber inserted into the second cartridge settlement unit to collect and store used toner from the photosensitive drum cartridge; a toner cartridge, the developing roller being disposed therein and exposed to the outside, the toner cartridge to supply stored toner and to move in the second cartridge settlement unit; and a connecting unit to connect the toner cartridge with the used toner chamber such that the toner cartridge reciprocates and rotates with respect to the used toner chamber.
According to another aspect of the present invention, the printing apparatus further includes first and second screws connected at an end of the toner cartridge and being spaced a predetermined distance from each other; a longitudinal hole formed in the used toner chamber to guide the first screw during the reciprocation; and a reaming hole formed in the used toner chamber to guide the second screw during the reciprocation and to rotate for a predetermined angle around the first screw, wherein the first and the second screws respectively include a flange portion having a diameter greater than diameters of the longitudinal hole and the reaming hole, to prevent a separation of the toner cartridge and the used toner chamber.
The printing apparatus may further include a position fixing unit to fix the used toner chamber to the body when the toner cartridge assembly is installed at the second cartridge settlement unit.
Furthermore, the position fixing unit may include first and second position deciding pins protruding around the second cartridge settlement unit of the body; and first and second position deciding holes disposed at the used toner chamber to receive the position deciding pins.
Furthermore, the printing apparatus may further include first and second stepped portions formed at the outside of the toner cartridge assembly in a direction of installation, wherein the press unit includes first and second movable members disposed in the second cartridge settlement unit to correspond to the first and second stepped portions and to be pushed by being contacted with the first and second stepped portions of the toner cartridge assembly, and first and second pressing springs to push the developing roller to the photosensitive drum by elastically pressing the movable members towards the toner cartridge assembly.